Like most of you, it seems like I am never done working. I needed to pop out a blog entry for the Embedded Newsletter so I thought I would run through some of the things I've been trying to get done while "on vacation" along with a couple of grips for the year.
I'll start with the upbeat things first. I recently received a Samsung 2232BW monitor that flickered. Turns out it is a well known issue and relatively easy to fix if you have a soldering iron handy which I do. You can find plenty of posts and YouTube videos on the issue and fix which is to replace at least three capacitors. The hardest part of this escapade was actually trying to get the caps.
Normally I would order them from Digi-Key but shipping for a handful of caps is more than the caps so I wandered down to my nearby Radio Shack. Of course, I needed at least three 1000uF caps and they had one. "No problem," they say, "Free shipping if you buy today." Of course they arrive almost a week later but the monitor is now up an running so I could work on my next project, setting up a file server and Squeezebox Server for my daughter. I've had Squeezebox Server running here for years but more on this later.
Setting up this server is something any techie can do. Twiddling with a cluster tends to be a bit more of a chore.
Adjusting my CENTOS Xen Cluster
I help out with the computers are a nearby private school my kids went to years ago. I have a pair of servers running CENTOS and CENTOS. There are a couple of other servers in the mix including a dedicated back up server. The two main servers run Drbd (Distributed Replicated Block Device) and LVM (logical volume management) along with Red Hat's clustering software and dedicated gigabit Ethernet links. It allows either machine to take up the slack if the other fails. This happens rarely but it saves me a trip in to fix things. Setting this up was an interesting exercise because it doesn't work this way out of the box.
The tweaking I needed to do this time around was due to my misunderstanding of Xen and overprovisioning. I did make sure I allocated memory based on physical memory but these are older machines with only four logical cores. The first thing I had to change was to dedicate a core to dom0, the host that handles I/O. The next step was to distribute the other VM (virtual machines) between the two machines so they would work properly on start up. Prior to this all the VMs would wind up on one machine making the default case slow.
It took a little tweaking of the cluster configuration so half of the VMs had one machine higher in their support group. It actually works. Now the VoIP phone VM runs on one server while the file and mail VMs run on the other.
It definitely pays to get a good handle on VM configuration for a dedicated application like this as well as embedded solutions. It does not pay to assume virtualization will simply work and provide optimum performance and reliability.
One of these days I'll try out Hadoop. But that is for another day.
I've had a Logitech Squeezebox Boom since it came out. I also run Squeezebox Server on one of my servers to handle it along with players that run on a few PCs around here. I like it because the web interface lets me control all the players. There is an Android app from Logitech that runs on my Droid Razr that does the same thing. It is handy but not at functional as the web interface. Actually the web interface is a touch clunky compared to the latest drag-and-drop web interfaces but it works well enough for me.
I wanted to get another Internet radio receiver but the price of the newer Squeezebox Radio is a bit steep. It lists for $179. It has a nice color LCD interface and plenty of buttons but I was originally looking for something cheap.
A search of the Internet didn't turn up anything inexpensive. There are some interesting options out there like devices supporting Apple's AirPlay and Sonos has some nice boxes but all of this was more expensive than Logitech's box.
As part of this exercise I found out about home theater receivers from the likes of Yamaha and Denon with Ethernet connections. Unfortunately, the compatability between any of these devices is nil. DLNA or Microsoft Media Center is about the only commonality among Internet radios and that support is rather poor. Yes, you can have access to your own music and playlists but management sucks when you have lots of devices.
Anyway, Best Buy wound up having a sale so I picked up the newer Squeezebox Radio at a significant discount. It is still expensive for an alarm clock but around here FM radios don't always get the stations I want.
Locking You Out Of Your Hardware
I figured since I am griping about Internet radios and the lack of any useful standard there I would rant about some recent announcements since I was looking into tablets too. The latest updates to the Amazon Kindle Fire and Barnes and Noble Nook Tablet are designed to prevent rooting.
In one sense, preventing users from rooting a device is supposed to prevent viruses from taking over your machine. Unfortunately, like most DRM, protecting a system from viruses and preventing rooting are distinct issues. True, the method of prevention may sometimes be the same but it is not a requirement.
Of course, the reason for preventing free use of the hardware has little to do with security or protection. Well, actually it does have to do with protection, of the vendors other revenue source. This goes back to the technique of giving away the razor to sell razor blades. In this case, the blades are apps, music and video.
These "security" updates are rather annoying and covert. There is a major Android tablet (I'll let you guess which one) that actually redirects the browser from the Android Market to the vendor's own app market. This is with an explicit URL entered in the browser. Of course, the idea is also to prevent side loading of applications (explicit download and install).
Lately the trend is to automatic and forced updates. My Sony Playstation no longer runs Linux and my Windows machine may have a new version of Internet Explorer soon whether it likes one or not. Oh well, this is progress, isn't it?
Ok, enough rants for this year.
Happy holidays. Now where is that coal.....